Subject: Prototype Mars Rover Completes Simulated Mars Trek
Douglas Isbell
Headquarters, Washington, DC June 10, 1997
(Phone: 202/358-1753)
Diane Ainsworth
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-5011)
RELEASE: 97-130
PROTOTYPE MARS ROVER COMPLETES SIMULATED MARS TREK
NASA's newest, six-wheeled prototype Martian rover --
nicknamed Rocky 7 -- has successfully passed its most rigorous
field test yet, traveling six-tenths of a mile over rugged, Mars-
like terrain, while conducting science experiments and snapping
580 photographs along the way.
The week-long series of field tests, carried out May 23-30 at
Lavic Lake, an ancient lake bed about 175 miles east of Los
Angeles, CA, was designed to simulate several weeks of a real Mars
rover mission and to test the rover's ability to drive much
greater distances than current rovers. In addition, Rocky 7
conducted five simulated science experiments in real-time and
collected samples of soil and rocks that would be retrieved and
returned to Earth by a later Mars mission.
"One of the chief objectives of these tests was to test Rocky
7's ability to traverse farther over a wide variety of terrain
with more Mars-like characteristics than we did in the last set of
tests in December 1996," said Dr. Samad Hayati, Rocky 7 task
manager at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA.
"The rover actually traveled about 80 percent farther than it
traveled in the last set of tests, over three distinct terrains,
using a minimum of instructions from us to guide its way."
The Rocky 7 rover represents the newest model of rovers that
may be sent to Mars in the years 2001 and 2003. It looks,
however, very similar to its predecessor, Sojourner, which will
land on Mars on July 4. Rocky 7 weighs slightly more than
Sojourner at 33 pounds and has about the same dimensions --
measuring 19 inches wide by 25 inches long by 12.5 inches tall.
Rocky 7 also sports the same six-wheeled chassis and spring-less
"rocker-bogie" mobility system, which allows the vehicle to
conform to the contours of the surface and scale objects almost as
tall as itself without tipping over.
Continued robotic exploration of Mars in the next century
will focus on the search for water and evidence to confirm hints
that life may have existed once in MarsŐ early history.
Successive Mars missions will be designed not only to examine the
planetŐs composition, atmosphere and weather, but also to identify
natural resources that could be mined and used for eventual human
expeditions to the red planet.
The southern side of Lavic Lake, located in the Twenty-Nine
Palms Marine Corps Base near Palm Springs, CA, was chosen for the
field tests because it is a playa, analogous to some regions of
Mars, with areas of lava flow, cracked mud, terrain strewn with
basalt rocks and an alluvial fan.
Rocky's travels began on a basalt flow covered with
cobblestones resting in a layer of wind-blown silt, which offered
a variety of obstacles for the robot to hurdle. Engineers tested
some of the rover's new features, such as a 12.5-inch manipulator
arm with four degrees of freedom. Mounted on the front of the
vehicle, the arm carried a "point reflectance" spectrometer that
could be extended four inches in any direction to study the color
of various surfaces. In future rover missions on Mars, science
instruments on the rover arm will help researchers determine the
composition of surface soils and rocks.
Engineers also tested a 4.5-foot, antenna-like mast, which
would be deployed once the future rover was out and about on Mars.
The mast has three degrees of freedom and can be used in much the
same way as an arm to deploy science instruments against rocks or
align them in the nadir, or down-pointing, position. Two science
instruments -- a Moessbauer spectrometer and a nuclear magnetic
resonance spectrometer -- were mounted on the mast to study surface
rocks with different types of coatings, such as red iron oxide and
desert varnish, which might be found on Mars. To carry out the
variety of science experiments performed during the week, Rocky 7
had to raise its mast 85 times.
Rocky 7 carried a pair of stereo imagers on the front and
back of the vehicle, which acted as its "eyes." The rover was
furnished with simulated descent imaging to recreate landing, then
asked to deploy its mast and begin each traverse and sequence of
imaging and science experiments.
"Images and science measurements were obtained in several
regions of the basalt flow," said Dr. Richard Volpe, chief
engineer on the rover development team at JPL. "This pavement of
basalt boulders and outcrops offered many terrain obstacles for
rover navigation and numerous targets for the rover to measure
cobbles and the underlying dust."
In the second journey, the rover set out over the playa,
strewn with craters and ejecta fields, and traveled into a crater.
Using its mast and arm, the vehicle was able to measure properties
of the mud-cracked floor. Rocky 7 also took images of its own
tire tracks to help scientists update its location.
"The rover conducted several long traverses across the playa
floor, taking images of the tracks left by its wheels so that we
could trace its path," said Dr. Raymond Arvidson, science team
lead and chairman of the Earth and Planetary Sciences Department
at Washington University, St. Louis, MO. "The tracks are used to
update positional information, after the observations are
completed and help us map out the vehicle's next route."
The last excursion was the most challenging -- an obstacle
course taking the rover over an alluvial fan extending from the
nearby mountains. There, Rocky 7 was asked to use its science
instruments to look for evidence that water had been transported
to the sediment and to explore the region for cobbles and boulders
that had come from volcanic rocks, just as it will do on Mars some
day.
"Imaging and spectroscopy data were acquired for the fan
rocks and fine-grained sediment, and samples of the sediment were
collected," Arvidson said. "The data are currently being analyzed
and will be used to fine-tune rover designs and operations and to
evaluate what can be learned about ancient lake environments and
desert pavement formation."
By the end of the week, the rover had returned 580 images to
remote operators in the field and those stationed at JPL. The
field test simulated 32 days of a real Mars rover mission.
Classrooms across the country and as far away as Finland
participated in a remote driving test on the last day of the field
work. The demonstration was designed to determine how well the
vehicle could be controlled remotely using a World Wide Web
operator interface called the Web Interface for Telescience. Six
schools in California, Oregon, Georgia, Idaho, Texas and Finland
participated in the exercise to command the rover from their
classrooms, as scientists will do one day from their home
institutions.
Additional information about the field tests is available on
the World Wide Web at:
http://wundow.wustl.edu/rocky7
More information about rover development for future Mars
missions is also available at:
http://robotics.jpl.nasa.gov/tasks/scirover.
The Rocky 7 rover development and field testing was
supported by JPL's Robotics and Mars Exploration Technology
Program Office for NASA's Office of Space Science, Washington, DC.
-end-